In general, portable terminals such as a mobile terminal, MP3 terminal, and tablet personal computer (PC) have a microphone and perform a function of transmitting and storing an audio signal received through the microphone through a wireless link. However, the microphone has +/− polarity. Therefore, when assembling a portable terminal, a microphone is falsely assembled or when a microphone having opposite polarity is connected to the portable terminal, the microphone cannot be driven. Further, in a handset, a headset, or an ear microphone, because pin allocation corresponding to a microphone is not standardized, a problem that compatibility does not perform exists.
FIG. 1 is a diagram illustrating a configuration of a conventional microphone and a portable terminal connected to the microphone.
Referring to FIG. 1, M+ and M− of the microphone are connected to a terminal 1 and a terminal 2 of the portable terminal through the terminal 1 and the terminal 2, respectively. The terminal 1 of the portable terminal is connected to a power supply terminal VCC through a pull-up resistor 21, the terminal 2 is connected to a ground terminal GND through a pull-down resistor 23, and a codec 25 inputs an output of the terminal 1 and the terminal 2 to MIC+ and MIC− input terminals, respectively. However, as shown in FIG. 1, when the microphone is connected with the polarity opposite to that of a microphone 10, a portable terminal 20 cannot normally control the microphone 10. That is, when M− of the microphone 10 is connected to the terminal 1 of the portable terminal 20 through the terminal 1, and when M+ is connected to the terminal 2 of the portable terminal 20 through the terminal 2, the mobile the terminal 20 cannot normally drive the microphone 10 connected with opposite polarity.
This is because pin allocation corresponding to a microphone is not standardized, as described above. Particularly, in a 4-pole ear microphone, in an American type 4-pole ear microphone, pins are arranged with a left right ground mic, and in an European type 4-pole ear microphone, pins are arranged with a left right mic ground.
Therefore, when pin arrangement of the portable terminal 20 is set in an American type, operation of an European type microphone cannot be controlled, and when pin arrangement of the portable terminal 20 is set in an European type, operation of an American type microphone cannot be controlled. That is, the portable terminal cannot control both European type and American type 4-pole microphones.